Target seeking device for missile guidance



sept. 14, 1965 A. WEL 3,206,144

TARGET SEEKING DEVICE FOR MISSILE GUIDANCE Filed Aug. 2l, 1962 5 Sheets-Sheet l Pr-oJectz'on a; Z

4164/0 WEL 7'/ Sept. 14, 1965 A. WELTI 3,206,144

TARGET SEEKING DEVICE FOR MISSILE GUIDANCE Filed Aug. 2l, 1962 3 Sheets-Sheet 2 A. WELT. 3,206,144

Sept. 14, 1965 TARGET SEEKING DEVICE FOR MISSILE GUIDANCE 3 Sheets-Sheet 3 Filed Aug. 21, 1962 L WP United States Patent() 3,206,144 TARGET SEEKING DEVICE FOR MISSILE GUIDANCE Arno Welti, Zurich, Switzerland, assignor to Albiswerk Zurich A.G., Zurich, Switzerland Filed Aug. 21, 1962, Ser. No. 218,280

Claims priority, application Switzerland, Sept. 8, 1961,

This invention relates to a self-guided missile and more particularly to a self-guided missile with la target seeking control unit contained therein.

When it is desired to collide two bodies, for example, a missile and a target object, moving in space, one may use, among other things, a so-called target seeking control whereby the missile automatically steers toward the target object by means of suitable direction finding devices. A known self-steering method of this kind which, because of its simplicity, has gained increased importance in the guided missile fields, is referred to as passive target-seeking steerage. In this method, energy sources of the target object, for example, heat rays, and suitable detectors in the missile, for example, infrared seeking heads, serve to locate the target object 'and to determine off course positions. The respective steering commands for the operation of the organs for change of movement, for example, rudders, are determined by computers.

Prior art target seeking guide systems utilize as the basis for the determination of the steering commands the following hit condition as prerequisite for the collision of the two moving bodies: The geometric angle between the line of sight S from the missile F to the target object Z and a fixed axis K which must be invariably constant in time. Referred to a missile-fixed polar coordinate system, this angle defines the so-called spherical distance d which stands in the following relationto the lateral, or horizontal, and vertical angles of the line f sight S, al, x1, and the fixed axis K, a2, \2:

The cost of instrumentation for the calculation of the off course positions on the basis of the above stated relation is considerable Iand constitutes a major disadvantage of the known` target seeking guide systems. In addition, the accuracy of the angle measurement must meet high requirements, again requiring complicated and expensive equipment.

The regulating method and means `according to the present invention avoid the above-mentioned disadvantages by utilizing the following concepts. A missile moving in spa-ce will positively collide with a target object also moving in space if the target object remains stationary in the image field of the detector in the missile. Let it be assumed only that the collision t-akes place in the future, that is, has not already occurred, and that the target object and missile are not moving parallel to each other. The immobility of the target image means that the line of sight from the missile to the target retains its direction in space invariably in time. Accordingly, the missile must be so steered -that there is no variation in the direction of the line of sight at any time. Then also, the hit condition is fullled at all times.

However, due to interferences resulting from external or internal influences, the missile may deviate from its hitting or striking course. A course deviation manifests itself in that the target image in the image field of the detector begins to shift. By properly steering the missile, the hit Icondition is again fulfilled and the target image comes to rest in the position maintained prior tothe shift. In the transitional phase, the direction of the line of sight in space may have changed, but this only delays the instant of collision; it does not make the collision impossible. The hit condition, therefore, does not constitute a rigid geometric condition; it has a transitory character. Every deviation from the course caused by interference, even if steering is infiuenced in the sense of the slowing of the movement of the target image, leads to the initial or starting phase of a new hit course of the missile. In other words, the hit or striking course is redetermined after every interference. Accordingly, it can be seen that the formulation for the conception of the liight regulator of the present invention differs fundamentally from that of known systems, where the flight regulator must serve to maintain rigidly the hit course initially assumed by the missile to the instant of collision with the target object.

The directional invariance of the line of sight may be checked, for example, by measuring the direction of the line of sight by location of the target object and the direction of a fixed axis, for example, that determined by a gyroscope in a missile-fixed polar coordinate system. The hit condition is fulfilled when the differences of correspon-ding angle coordinates of both directions remain constant in time. The conditions for the fulfillment of the hit comamnd 4can be satisfied also without reference to a fixed axis, that is, without the use of a gyroscope unit, if, as taught by the present invention, not one but two detectors for locating the target object are provided in the missile, which together form a stereoscopic detector unit. From the stereoscopic observation of the target from the missile it is, in fact, possible to derive criteria for maintenance of the hit condition as well as for the stabilization of the missile.

In accordance with the present invention, automatic regulation of the movement of a self-guided missile toward a target is provided by the use of two ray detectors whose optical axes are directed toward the same target, the variations in time of the angle difference (a1-2), of the angle sum (x1-H2) and of the ratio being regulated to the value zero, where al, K1 and a2, A2 are the momentary values of the continuously measured position angles of the two optical axes in relation to a missile-fixed coordinate system.

Accordingly, it is an object of this invention to provide an improved method for the automatic regulation of the movement of a self-guided missile toward a target.

Another object of this invention is to provide an improved target seeking guidance system which does not require the use of complicated and expensive equipment.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of the preferred embodiments of the invention, as illustrated in the accom-` panying drawings.

In the drawings:

FIG. 1 is a geometric illustration of spatial conditions prevailing in principle in target pursuit;

FIGS. 2, 3 and 4 are graphs indicating image points used in the system of the present invention;

FIG. 5 illustrates in block diagram form a flight regulator of the present invention;

FIG. 6 shows an infrared ray detector which may be used in the system of the present invention, illustrated in FIG. 5 of the drawings;

FIGS. 7, 8, 9 and 10 show circuits which may be 3 employed for the individual stages of the flight regulator illustrated in FIG. 5;

FIG. 11 shows in block diagram form a ight regulator in which means are provided for the regulation of the convergence of the two detector axes;

FIG. 12 is a diagram of a circuit arrangement for the target tracking control of a ray detector;

FIG. 13 is a diagram of a circuit arrangement using the principle of'information crossing for the target tracking control by two ray detectors;

FIG. 14 is a block diagram of a llight and convergence regulator in which the computing attachment is replaced by direct crossed coupling of the target position data and the ilight control commands; and

FIG. 15 is a vector diagram provided to facilitate the explanation of the operation of the regulator illustrated in FIG. 14 of the drawings. Referring to the drawings in more detail, and particularly to FIG. 1, there is shown the spacial conditions prevailing in principle in target pursuit by geometrical representation. For a better understanding of the invention, let target Z move on the course Kz and the missile F on the course Kf toward a point of collision T in the direction of the arrows. Furthermore, let the longitudinal axis of the missile coincide with its direction of ght. At the ends of a base B fixed 4in the missile F there are arranged two ray detectors D1 and D2, both of which have their optical axes, the lines of sight S1 and S2, respectively, aimed at the target Z. The plane formed by the base B and the missile course Kf is designated the flight horizon plane and the plane formed by the base B and the lines of sight S1 and S2 is designated the sight horizon plane. The lateral or horizontal angles a1, a2 and vertical angles A1, A2 of the lines of sight S1 and S2, used for target nding, are detined with reference to the base B and the plane which it forms with the vehicle axis. The course lines Kz and Kf form the target fall plane which intersects the sight horizon plane in line V, which may be termed the sighting line of a single imaginary detector in the center of base B.

The hit condition is fulfilled when the superposed target image formed by the two ray detectors stands still in the direction-invariant sight horizon, i.e. when Mn is a constant. This is true of any static hit course. For the transitional phases, during which the missile is to be changed over from one to another static hit course as a result of an interference, an additional condition is derived in the following manner. The hit condition can be illustrated in a so-called phase space, a diagram which represents the state of two quantities in mutual interconnection. According to FIG. 2 of the drawings, the present position angles a and )t of the lines of sight S1 and S2 directed toward the common target Z are correlated in the image points P1 and P2 as Cartesian coordinates. Positions and movements of the image points are quite arbitrary in FIG. 2, thereby expressing absence of hit expectation and absence of symmetry. FIG. 3 of the drawings, on the other hand, shows a state where the hit condition is fulfilled and also where the desired symmetrical position of the lines of sight with respect to the target fall plane is achieved. In this state, as indicated in FIG. 3 of the drawings, the two image points P1 and P2 coincide and remain at rest. The immobility of the image points in the image field of the ray detectors exists evidently when the position angles a1, a2, k1 and A2 do not change in time, which may be formulated as follows:

The condition of symmetry further requires that the mutually corresponding position angles of the two lines of sight S1 and S2 must be at all times the same, hence their differences must be zero, that is: Aa=0 and Ax=0,

In order to avoid the loss of the hit command during an interference phase and also during the transition to a new static hit course, proceedings must be performed according to rule, as is illustrated with reference to the phase space diagram in FIG. 4 of the drawings. The originally separated image points P1 and P2 must meet in a common point, for example, point Pt and must come to rest at point Pt. Accordingly, the movements of points P1 and P2, like those of the missile to the target, must be steered so that the condition for collision in the hit image point Pt is fulfilled at all times. This is the ca-se when the connecting line of the two image points P1 and P2 maintains its direction in the diagram in time, that is, when the angle ,8, as shown in FIG. 4 of the drawings, remains constant. The hit condition for the movement of the image points in the space phase thus is Ace -A-i-a constant In summary, the following conditions exist for obtaining a collision of a missile with a target:

Aa=a constant, maza constant, and

Aa a A- constant The method of the present invention for the automatic regulation of the movement of a self-guided missile toward a target now includes directing two ray detectors with optical axes toward the same target, the time variations of the angle difference er1-a2' of the angle sum A14-x2, and of the ratio being the momentary values of the continuously measured lposition angles of the two optical axes in relation to a mls- Sile-fixed coordinate system.

This invention also relates to a device for carrying out the method described hereinabove. The device of the present invention includes two ray detectors, both arranged for the independent pursuit of the target object and each controlling an angle transmitter which furnishes the momentary lateral or horizontal and vertical angles of the lines of sight relatively to a missile-fixed polar coordinate system. The device further includes an attachment with networks for the generation of two control signals, which form a measure of the time deection of the difference of the lateral or horizontal angles or, respectively, of the sum ofthe vertical angles, each influencing a setting motor of two axes of the flight control in the sense of a reduction of the angle difference variation in time, as well as by a resistance bridge in which two opposite bridge branches constitute a resistance proportional to the difference of the lateral angles and the other two opposite bridge branches constitute a resistance proportional to the difference of the vertical angles, and one bridge diagonal has connected to it a voltage source, and a differential member is arranged in the zero branch, the control v0ltage taken from the differential member influencing the setting motor of a third axis of the ight control in the sense of a reduction of every variation in time of the voltage in the zero branch.

To more clearly understand the devices or systems of the present invention, reference may be had to FIGS. 5 to 15 of the drawings. A flight regulator of the present invention is shown in FIG. 5 of the drawings which includes, for the location of the target object Z, two horizontally and vertically movable ray detectors 1 and 2, which by a servo-motor set 3, 4 for each are directed with the optical axis toward the target object Z. Each ray detector furnishes an error voltage, which constitutes' a measure of the deviation of the optical axis from the line of sight S1, S2 and which can be processed in con- -trol stage 5, 6 into control'signals for the control of the servo-motors in the sense of a reduction of the deviation.

Each of the ray detectors 1 and 2 indicated in FIG. 5 of the drawings may include, as shown in FIG. 6 of the drawings, an objective lens 7, an image iield scanner 8, a eld lens 9, and a radiation-sensitive cell 10. Two pivot axes 11 and 12 of the ray detector are shown disposed normal to each other. The image field scanner 8 is a rotating raster disc having a pattern such that an impinging ray is modulated within the image eld dependent of the location of the image point produced on the raster disc. By comparison of the similarly modulated output voltage of the cell 10 with a reference voltage characterizing the direction of the optical axis of the ray detector, which reference voltage is derived from the oscillating movement of the ray detector, there is obtained upon migration of the image point out of the optical axis the error voltage added to the control stage S or 6 of FIG. 5 of the drawings.

As shown in FIG. 5, each ray detector has furthermore mechanically coupled with it an electric angle transmitter or resolver 13, 14 having two electrical outputs. At one output, there occurs a voltage proportional to the lateral angle al, a2 and at the other output a voltage proportional to the vertical angle k1, k2, the angles a1, A1 being the coordinates of the line of sight S1 and the angles a2, 12 being the coordinates of the line of sight S2, referred to a missile-xed coordinate system.

The portion of the ight regulator outlined in dash-dot lines in FIG. 5 of the drawings is an attachment which, in the present case, is an analog computer determining from the quantities a1, a2, A1, A2 the control quantities required to influence the iiight control. The attachment includes a network 15, 16 respectively for the formation of the angle difference A \=A1r- \2 and the angle difrerence Aa=a1a2 and a network 17 for the formation of the angle sum a-A=)\1-}- \2. The control quantities taken from the networks 17 and 16 are supplied over differentiating networks 18 and 19, respectively, to a setting motor for each for the operation of the vertical (H) and lateral or horizontal (S) steering or guidance of the missile. In addition, the control quantities taken from the networks and 16 enter a computer stage 20 in which a signal proportional to the ratio of the two control quantities is generated which, after passing through a diierentiating network 21, inuences the setting motor for the operating ofthe transverse steering (Q) of the missile.

In FIGS. 7 to 10 of the drawings, there are schematically illustrated examples of circuits for the practical construction of the attachment shown in FIG. 5 of the drawings. As angle transmitters there serve rotary potentiometers whose sliding wipers are mechanically connected with the pivot axes 11, 12 shown in FIG. 6 of the ray detectors 1 and 2 of the regulator of FIG. 5 in such a way that the position of each wiper corresponds to an angle coordinate of the respective ray detector. v

As can be seen in FIG. 7, a pair of rotary potentiometers 31 and 32 measures the vertical angles )r1 and A2 of the two ray detectors. The two potentiometers 31 and 32 are connected serially to each other across a voltage source 33 so that a voltage U between output terminals 34 and 35 each connected to a wiper arm of one of the potentiometers 31, 32 is proportional to the angle sum A14-A2.

The angle difference :x1-a2 is derived from an arrangement illustrated in FIG. 8 of the drawings. In FIG. 8, a pair of rotary potentiometers 41 and 42 are connected in parallel relationship across a voltage source 43 in such a way that the voltage U between output terminals 44 and 45 connected to wipers of the potentiometers 41 and 42 is proportional to the angle difference er1-a2.

The angle difference can be derived also with an arrangement illustrated in FIG. 9 of the drawings. In contrast to the previous examples, with a connection of the rotary potentiometers 51 and 52 as shown in FIG. 9, the

resistance R operative between the output terminals 53 and 54 coupled to the wipers of the potentiometers 51 and 52 is proportional to the angle difference :x1-a2.

The circuit arrangement according to FIG. l0 is suitable for the derivation of a signal which is dependent on the differential quotient d(A/A7\)/dt, as is provided for steering the cross rudder of the missile. For this purpose, four angle transmitter pairs .as shown in FIG. 9 are combined in a bridge connection. The opposite bridge branches 60 and 61 represent each a resistance proportional to the angle difference Aa=a1-a2, and the opposite bridge branches 62 and 63 represent each a resistance proportional to the angle difference A)\=}\1 \2. To one bridge diagonal a voltage source 64 is connected. The voltage at the other bridge diagonal is proportional to the quotient (Aa-mO/(Aa-i-AM; it is conducted over a differentiating network including condensers 65, 66 and a resistance 67, and an amplier 68 to output terminals 69. The differentiated voltage is dependent on the time derivanon dma/mgmt.

It can be seen that the rabove example of the circuit indicates that the means for carrying out the regulating method according to the invention, based on the zero method, is relatively simple and inexpensive. It can further be shown that a missile equipped with the described regulating arrangement hits the target under all circumstances at suiicient ight velocity. Insuicient accuracy and aging of the optical, mechanical, or electrical components of the detectors or of the iiight regulator, eccentric thrust of the drive means, angle of incidence between the longitudinal axis of the missile and the trajector tangent, have no influence on the execution of the command given to the missile, i.e. to hit the target. The path which the missile takes is not predetermined. After every external or internal interference, with the exception of a breakdown, no matter of what kind, the flight regulator steers the missile into a new hitting cou-rse, that is, the trajectory to the target is always redened. The precision ordinarily required for remote steering tasks is not necessary; the tolerance limits may be wide. In all regulating, controlling, and computing operations only relative quantities are involved. Thus, the proposed solution gives a broad adaptation of steering to the task to be fullled by the missile.

When using two ray detectors, the problem is to concentrate the two detector axes on a single target. If several targets appear in the image iield of the ray detectors, the ray detectors may focus two dicerent targets, i.e. one detector may focus on one target and the other detector may focus on the other target, unless special precautions are taken. Conv/erging detector axes are practically parallel if the target is far removed. From this situation, there is obtained a static convergence condition having the relations:

2a=constant and 11:0

is in part already present in the ight regulator illustrated v in FIG. 5. FIG. 1l shows the block circuit diagram of the flight regulator including means for convergence regulation. The blocks shown in FIG. 1l which aresirnil'ar to those shown in FIG. 5 are indicated by the same symbols. As additional stages there appear in FIG. l1 a network 22 for the formation of the angle sum @azul-+112 as well as two diferentiating networks 23 and 24 for the formation of the lateral derivation dau/dt or respectively :IAA/dt. The error voltages resulting at the differentiating networks inuence both the control stages and 6 which are provided for the self-steering of the two ray detectors 1 and 2. This results in a coupling of the two control ci-rcuits, which will be discussed below.

In FIG. 12 is represented schematically a known arrangement for the self-steering or target tracking of a ray detector shown in FIG. 6. The image eld scanner 8 shown in FIG. 12, and indicated also in FIG. 6, is a quadrant disc which rotates uniformly in the image eld of the ray detector and which lets the target image point Pz fall periodically on the radiation-sensitive cell 10 during a quarter revolution. The error Voltage produced in cell 10 passes through an amplifier 70 to the contact 71, revolving synchronously with the quadrant disc 8, of a ring distributor having four segments 72, 73, 74 and 75. Segments 72 and 74 are connected with two mutually oppositely acting coils of a polarized relay 76 and segments 73 and 75 are connected to a second polarized relay 77. Each of these relays has a change-over contact 78, 79 which connects one of the two opposing exciter windings 80, 81Vand 82, S3 of an electric motor 84, 85 with a current source 86, 87. The electric motor 34 is to be coupled with the pivot axis 12 shown in FIG. 6 for vertical displacement of the ray detector and the electric motor 85 is to be coupled with the pivot axis 11 of FIG. 6 for the lateral displacement of the detector.

As can be understood from FIG. 12, the target point Pz is present momentarily in the upper right of the image eld. Each time cell 10 is acted upon by the target image point Pz, current flows in the ring distributor, namely, for the direction of rotation of the quadrant disc 8 and of the revolving contact 71 shown by arrows successively over the segments 72 and 73. Thereby, the relays 76 and 77 are energized periodically, relay 76 being energized through the upper winding, and relay 77 being energized through the right hand winding shown in FIG. 12. By the contacts 78, 79 the electric motors 84, 85 are connected impulse-wise, which oscillate the ray detector upward and to the right in such manner that the detector axis approaches the target. The target image point Pz then advances toward the center of the image eld, until the error voltage finally disappears.

The additional control of the self-steering circuits of both ray detectors by the error voltages of the convergence regulator may now occur for example as follows: To each of the named polarized relays 76, 77 in the control circuits of both ray detectors an auxiliary relay is assigned in the form of another polarized relay, whose change-over contact is connected in parallel with that of the already existing relay. The windings of the two auxiliary relays for the additional lateral displacement of the two ray detectors are connected with each other so that during common energization of the two auxiliary relays on the basis of a lateral error voltage the two electric motors for the lateral displacement rotate in opposite directions. In like manner, the auxiliary relays for the vertical displacement of the two ray detectors are connected with each other.

In this way, therefore, the regulation of the axis position of each ray detector occurs on the basis of target position information obtained from both ray detectors. Such a crossed coupling of the control information results in a high degree of stability of regulation.

It has been found that for the convergence regulation one may dispense with a computing attachment, that is, direct information crossing within the self-steering circuits of both ray detectors can be used with equal success. An example of this is illustrated schematically in FIG. 13. The designations are the same as those in FIG. l2. The two identical self-steering circuits are coupled together over resistances 90 in such manner that the error signal taken from amplifier 70 of one control circuit is supplied not only to the respective ring distributor, but also to that of the other control circuit. An initial Cil convergence off-position causes, over the crossedk cou-A pling, currents in the. ring distributors and corresponding excitations of the vertical and lateral relays 76, 77 and of the axis-setting motors (not shown in FIG. 13) so that the axes of the two ray detectors always converge.

In the circuit of FIG. 13, two control circuits are designated R and L, to indicate that they belong to the ray detectors D1 and D2 arranged at the right and left ends of the base B illustrated in FIG. 1. In the position of the target image point Pz in the image iield of the ray detectors as entered in FIG. 13, the vertical relay 76 and the lateral relay 77 in the control circuit L are energized in the sense that the axis-setting motors of the left ray detector move the detector axis toward the target image point to the right and upwardly. In control circuit R only the lateral relay 77 is energized solely from the. right ray detector, whereby the respective detector axis is moved to the right. Due to the crossed coupling,

however, current flows also over the right ring distributor, originating from the amplifier 70 of the control circuit L, with the result that also the vertical relay 76 of the control circuit R is energized in the same sense as that of the control circuit L. With that, however, the target image point Pz in the right image eld falls into the right lower quadrant. In the control circuit R there now occurs from the ring distributor a current which acts in opposite sense on the vertical displacement of the right detector axis. Through the crossed coupling this current causes the upward movement of the left detector axis in control circuit L to slow down. Therefore, the axis of the right ray detector moves upwardly more and that of the left ray detector moves upwardly less than would be the case without crossed coupling, that is, the initially diverging detector axes strive toward convergence.

In a similar manner, a simplification can be achieved also in the flght regulator by replacing the computing attachment by a direct crossed coupling of the target position data and ight steering commands. An example of this is illustrated schematically in FIG. 14 of the drawings. The ray detectors 1, 2 with their devices 3 to 6 for target location and pursuit have remained in principle the same as in the circuit shown in FIG. 5. For the steering of the missile, whose main drive acts for example in the direction of its longitudinal axis, there are provided two jet rudders 101, 102 of equal thrust, which are arranged on both sides of the center of gravity of the, missile for horizontal and vertical oscillation. For the movement of the jet rudders 101, 102 there is provided a servo-motor assembly 103 and 104, respectively.

It can now be shown that the above formulated hit and symmetry conditions are fullled if at all times the axis of the right jet rudder 101 is set parallel with the axis of the left ray detector 2, and the axis of the left jet rudder 102 with the axis of the right ray detector 1. The momentary position coordinates of the target jointly furnished by the two ray detectors contain implicitly all information required for the light and convergence regulation. The transformation of these data into steering commands for the. servo-motor assemblies 3, 4, 103 and 104 is brought about solely by the crossed coupling or information crossing, that is, without computing members.

In FIG. 15 are shown the horizontal components ofl direction indicated by the vector S33 lies away from ,the

center of gravity S of the missile, as does also the resulting target direction vector Z3, causing a torque M which turns the missile in the sense of a reduction of the target olf-position.

As can easily be demonstrated, after the information crossing, the difference of the lateral angles Aa=a1a2 included in the vector sum of the target direction vectors appears unchanged in the vector sum of the thrust direction vectors as indicated in FIG. 15. Also, the sum of the vertical angles 21 \1{ \2 remains intact upon crossing. However, the angle sum Za=1 ia2 and the angle dierence A0\=)\1- \2 change their sign.

Information crossing, therefore, means a transformation of the occurring target direction information into the steering information to determine the adjustment of flight control. In this transformation, the directional sign of certain information components is maintained, while others change it. It is found that by the information crossing, not only are the equations occurring in the hit and convergence conditions imitated analogously in a wider sense, but also the signs are correctly made Without additional measures. Thus, the orientations of the lateral and vertical steering components Aa and ZA are maintained in crossing. Accordingly, the thrust and target direction vectors merge parallelly. Instead, the transverse lsteer-ing :component Aon/AA changes its directional sign; the rotation picked up by the target direction vectors and the torque produced by the thrust vectors at the missile are directed oppositely to each other.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. In a missile guidance device, the combination comprising means providing a missile-xed coordinate system including a plane defined by the flight direction of the missile and a missile-fixed base line transverse to said ilight direction; a pair of target-object-seeking ray detectors each positioned at a respective end of said base line and each responsive to rays from a target object and having an optical axis, each ray detector including means producing error voltages proportional to deviations of its optical axis from the line of sight therefrom to the target object; angle transmitter means responsive to said error voltages from each of said ray detectors providing continuous indications of the momentary Values of the lateral and vertical angles of the optical axes of said detectors with respect to said missile-fixed polar coordinate system; and missile guidance means, including guidance control means connected to the output of said angle transmitter means.

2. The combination as set forth in claim 1, further comprising an attachment including networks connected to said `angle transmitter means for generating two control signals respectively indicative of the time derivative of the difference of said lateral angles and the time derivative of the sum of said vertical angle; and means, including two setting motors, each controlled by a respective one of said two control signals, for reducing the time derivative of the angle difference.

3. The combination as set forth in claim 2, further comprising a resistance bridge including two opposite bridge branches each having a resistance proportional to the difference between the lateral angles, two other bridge branches each having a resistance proportional to the difference of the vertical angles, a voltage source connected to one bridge diagonal and a differentiating member disposed in the other diagonal of said bridge and means, including a third setting motor controlled by the voltage from said differentiating member for reducing the time derivative of the Voltage in said other diagonal.

4. The combination as set forth in claim 3, further comprising means for combining the error Voltage from each of said ray detectors in said reducing means.

References Cited by the Examiner UNITED STATES PATENTS 2,958,135 1l/60 Lakin 250-203 X BENJAMIN A. BORCHELT, Primary Examiner. SAMUEL FEINBERG, Examiner. 

1. IN A MISSILE GUIDANCE DEVICE, THE COMBINATION COMPRISING MEANS PROVIDING A MISSILE-FIXED COORDINATE SYSTEM INCLUDING A PLANE DEFINED BY THE FLIGHT DIRECTION OF THE MISSILE AND A MISSILE-FIXED BASE LINE TRANSVERSE TO SAID FLIGHT DIRECTION; A PAIR OF TARGET-OBJECT-SEEKING RAY DETECTORS EACH POSITIONED AT A RESPECTIVE END OF SAID BASE LINE AND EACH RESPONSIVE TO RAYS FROM A TARGET OBJECT AND HAVING AN OPTICAL AXIS, EACH RAY DETECTOR INCLUDING MEANS PRODUCING ERROR VOLTAGES PROPORTIONAL TO DEVIATIONS OF ITS OPTICAL AXIS FROM THE LINE OF SIGHT THEREFROM TO THE TARGET OBJECT; ANGLE TRANSMITTER MEANS RESPONSIVE TO SAID ERROR VOLTAGES FROM EACH OF SAID RAY DETECTORS PROVIDING CONTINUOUS INCIATIONS OF THE MOMENTARY VALUES OF THE LATERAL AND VERTICAL ANGLES OF THE OPTICAL AXES OF SAID DETECTORS WITH RESPECT TO SAID MISSILE-FIXED POLAR COORDINATE SYSTEM; AND MISSILE GUIDANCE MEANS, INCLUDING GUIDANCE CONTROL MEANS CONNECTED TO THE OUTPUT OF SAID ANGLE TRANSMITTER MEANS. 